This invention relates to medical methods and apparatus, and more particularly to methods and apparatus for installing a tubular graft in a patient for such purposes as bypassing an occlusion or narrowing in the patient""s tubular body structure. More particularly, this invention relates to instrumentation and methods for providing an opening in a side wall of the patient""s body structure, and instrumentation and methods for attaching the tubular graft to the patient""s body structure at the opening that has been made.
The invention is applicable to making anastomotic connections between all body conduits. For example, the invention also has application for attaching coronary artery bypass grafts. Specifically, connection methods and apparatus are provided for attaching the graft ends to the coronary artery and the aortic artery. In the case of the internal mammary artery, connection is required at the coronary artery only.
During coronary bypass surgery vein grafts are attached to the ascending aorta, i.e., a proximal anastomosis, and to the coronary artery, i.e., a distal anastomosis. The vein graft bypasses the diseased or stenotic region of the coronary artery allowing blood to flow through the graft and perfuse the heart distal to the stenosis site.
An early step in the procedure is to create a hole in the artery to which the vein graft is to be connected. A precisely controlled hole and geometry is needed to optimize the performance of the anastomosis. According to conventional techniques, a scalpel and a punch are used. A slit is first made in the aortic wall. The slit is typically wider than the punch, such that the distal end of the punch can be inserted through the slit into the lumen of the artery. An aortic punch consists of an anvil portion and tube that are relatively movable with respect to each other. The aortic punch removes a portion of the wall by crushing or forcing the anvil section inside the artery lumen, against the tube positioned outside the artery wall. The compressive action of the anvil against the tube shears and crushes the tissue between the anvil and the tube.
The method has several disadvantages. The hole produced is typically very irregular and variable in size. Moreover, the initial scalpel slit, typically extends beyond the opening made by the aortic punch and ay result in leakage. The surrounding residual tissue, which has been left behind, is usually damaged due to the crushing action. This damage can produce a biological healing response for the damaged cells, which can cause inflammation and other adverse events at the critical anastomosis site.
The conventional procedure to make the connections after the hole has been made is by hand-sewing or suturing. It will be appreciated, however, that making such connections by suturing can be extremely difficult, time-consuming, and dependent on the skill of the physician for the quality of the results. There is also increasing interest in less invasive procedures which tend to impose constraints on the physician""s access to the sites at which graft connections must be made and thereby make it more difficult or even impossible to use suturing to make such connections (see, for example, Goldsteen et al. U.S. Pat. No. 5,976,178, Sullivan et al. U.S. Pat. No. 6,120,432, Sullivan et al. U.S. patent application Ser. No. 08/869,808, filed Jun. 5, 1997, concurrently filed U.S. patent application Ser. No. 09/187,364, filed Nov. 6, 1998 and Peterson et al. U.S. Pat. No. 6,152,937, all of which are hereby incorporated by reference herein in their entireties). Conventional suturing techniques may contribute to the failure of the anastomosis. The sutures themselves may initiate injury to the graft vessel.
In view of the foregoing, it is an object of this invention to provide improved and simplified apparatus and methods for providing an opening in tubular body conduit.
It is still another object of this invention to provide improved and simplified methods of making structures that can be used as medical connector apparatus.
It is also an advantage of the invention to provide an improved and consistent anastomosis result, without the reliance on the technique and skill of the physician.
These and other objects of the invention are accomplished in accordance with the principles of the invention by providing improved apparatus and methods for installing a guide structure in a patient between two locations along the patient""s circulatory system that are to be connected by a bypass graft.
Instrumentation is provided for facilitating cutting an opening in a side wall of a body conduit. A tubular structure is provided which defines a lumen and has a sharpened distal end portion configured to cut a section of the body conduit to create the opening. A tissue holding structure is also provided which is axially movable within the lumen of the tubular structure. The tissue holding structure includes a piercing portion to permit passage of the tissue holding structure through the body conduit from an entrance side adjacent the tubular structure to an exit side thereof. The tissue holding structure also includes a retention member to secure the body conduit to the tissue holding structure during movement of the tissue holding structure to approximate the entrance side of the section of the body conduit and the sharpened distal portion of the tubular structure which enables the sharpened distal end portion to cut the section of body conduit.
After the section of body conduit has been cut, the tissue holding structure and the section of body conduit secured thereto by the retention member are proximally movable into the lumen of the tubular structure.
In one embodiment, the retention member is a barb that is resiliently biased radially outwardly in order to secure the section of body conduit. The barb may be deflected radially inwardly during the distal passage of the tissue holding structure through the section of the body conduit.
The piercing portion may be a needle catheter having a sharpened distal end portion to permit distal passage of the tissue holding structure through the section of body conduit. The tissue holding structure further may include a barb support member which supports the barb thereon and is axially movable within an internal lumen of the needle catheter. The needle catheter may be sized to deflect the barb radially inwardly during distal movement of the barb support member through the internal lumen of the needle catheter, and to subsequently allow the barb to return to an outwardly extending orientation after passage through the internal lumen. The barb support member may have an atraumatic distal tip portion. In a preferred embodiment, the barb support member extends distally from a flexible catheter.
The instrumentation may also include a connector for providing an anastomosis between the body conduit and a new length of body tubing comprising a first plurality of fingers for engaging an inner wall of the body conduit, a second plurality of fingers for engaging an outer wall of the body conduit, and a plurality of engagement members for securing the new length of body tubing to the connector. In one embodiment, the first plurality of fingers, the second plurality of fingers, and the engagement members are resiliently disposed radially outward.
Further instrumentation may be supplied to install the connector, including a connector support defining a longitudinal axis. The connector support may have a first retention structure to retain the first plurality of fingers towards parallelism with the longitudinal axis and a second retention structure to retain the second plurality of fingers towards parallelism with the longitudinal axis, such that the engagement members are disposed radially outwardly to facilitate attachment of the new length of tubing thereto. In an embodiment, the connector support and the instrumentation for cutting an opening in the body conduit may be one unit. Consequently, the connector support may define an interior lumen for receiving the tubular structure and tissue holding structure therethrough.
In a preferred embodiment, the first retention structure is an annular sleeve for retaining the first plurality of fingers distally towards parallelism with the longitudinal axis. The first retention structure retains the first plurality of fingers in a configuration having a dimension smaller than the opening in the body conduit.
The second retention structure may be a member having a projection received in a corresponding opening in each of the second plurality of fingers to retain the second plurality of fingers distally towards parallelism with the longitudinal axis. The second retention structure may also be an annular sleeve to retain the second plurality of fingers proximally towards parallelism with the longitudinal axis.
Instrumentation may also be provided to assist in the attachment of the new length of tubing to the connector. The new length of tubing may have a direction of natural fluid flow. For example, the saphenous vein normally has one-way valves to promote fluid flow in a single direction. In order to assist in the positioning of the new length of tubing, a sleeve sized for passage within the new length of tubing may be provided. The sleeve has an indicator to provide a visual indication of the direction of natural fluid flow. Additional instrumentation may include a pressure-application tool for facilitating the piercing of the new length of tubing by individual ones of the engagement members to secure the new length of tubing to the connector. The pressure-application tool may have a distal sleeve portion with an internal lumen sized such that individual ones of the engagement members may be received therein. The sleeve provides substantially uniform pressure to the new length of tubing about the engagement member to pierce the new length of tubing by the engagement member.
A method is also disclosed for performing an anastomosis between a body conduit and a new length of tubing which includes providing a tissue holding structure having a retention member to secure the body conduit to the tissue holding structure. Another step may be securing the retention member to the body conduit by at least partially inserting the tissue holding structure into the body conduit.
The method may also include providing a tubular structure having a sharpened distal portion. The body conduit and the sharpened distal portion of the tubular structure are approximated by relative movement of the tissue holding structure towards the tubular structure.
The method may also include cutting a section of the body conduit with the sharpened distal portion of the tubular body structure to provide an opening in the body conduit. The new length of tubing is attached to the body conduit adjacent the opening made by the cutting.
In a preferred embodiment, the method also includes providing a connector defining a central opening and having a first plurality of fingers for engaging an inner wall of the body conduit, a second plurality of fingers for engaging an outer wall of the body conduit, and a plurality of engagement members for securing a portion of the new length of body tubing to the connector. Attaching the new length of tubing to the body conduit adjacent the opening is performed by securing a portion of the new length of body tubing to the connector with the plurality of engagement members, engaging the inner wall of the body conduit with the first plurality of fingers, and engaging the outer wall of the body conduit with the second plurality of fingers.
In another embodiment, the method includes providing a connector support defining a longitudinal axis and having a first retention structure for retaining at least one of the plurality of fingers towards parallelism with the longitudinal axis, and prior to securing the portion of the new length of tubing to the connector, mounting the connector coaxially about the connector support and retaining one of the plurality of fingers with the retention structure.
Installation of the connector is performed by inserting the first plurality of fingers into the opening, releasing the retention structure to allow the first plurality of fingers to engage the inner wall of the body conduit, and releasing another retention structure to allow the second plurality of fingers to engage the outer wall of the body conduit.